1. Field of the Invention
This invention relates, generally, to focus beam analysis of high power lasers. More particularly, it relates to focus beam analysis of multi-kilowatt fiber lasers.
2. Description of the Prior Art
Conventional measurement of a laser beam waist from a focused laser beam requires the use of a measurement system including a spinning needle, a rotating aperture or slits, or movement of either a focus lens or a pixelated detector along the optical axis of the laser beam. Use of any of these known measurements systems requires interruption of the process beam.
The prior art includes no methods to provide real time, in-line measurement of a laser based optical system, i.e., all prior art systems require insertion of a measurement system and such insertion requires interruption of the process beam.
Multiple patents, such as U.S. Pat. Nos. 5,064,284, 5,069,527, 5,078,491, 5,100,231, 5,214,485, 5,267,012 and 5,459,565, disclose methods for analyzing a multimode laser beam by passing the beam through a rotating knife edge followed by translating the focal point along the optical axis to a detector.
U.S. Pat. No. 8,237,922 discloses a method for real time measurement but such method also requires disruption of the process beam.
Some laser beam analysis equipment can be placed prior to the focus lens by looking at bleed light from a turning mirror. However, that technique provides information upstream of the optic and no information downstream of the optic which is the more important point of the system, i.e., the final focus lens or debris shield.
In view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the art how an apparatus for focus beam analysis that does not require interruption of the process beam could be provided.